BDNF and anxiety disorder: The human BDNF[V66M] polymorphism, which is associated with altered dendritic trafficking of BDNF mRNA, changes in hippocampal volume, impaired hippocampal-dependent memory and NMDA-receptor dependent synaptic plasticity, and extinction of conditioned aversive memory, has been implicated in anxiety disorders (Chiaruttini et al., 2009; Yu et al., 2009; Ninan et al., 2010).